Hi,
Page mother is not in cat 1… page mother CALLS cat1, cat2, cat3.
I can give you admin access to wpress if you want.
a) CONTENT CAT 1 haves sub categories: CAT 2 and CAT 3? NO
CONTENT CAT 1 is a post of CAT 1.
CONTENT CAT 2 is a post of CAT 2.
CONTENT CAT 3 is a post of CAT 3.
CAT1, CAT2, CAT3 are called by MOTHER PAGE with your plugin.
So in mother page I will have a menu with 3 links to cat1, cat2 and cat3